package com.trt.contentcenter.configuration;

import com.alibaba.cloud.nacos.NacosDiscoveryProperties;
import com.alibaba.cloud.nacos.ribbon.NacosServer;
import com.alibaba.nacos.api.exception.NacosException;
import com.alibaba.nacos.api.naming.NamingService;
import com.alibaba.nacos.api.naming.pojo.Instance;
import com.alibaba.nacos.client.naming.core.Balancer;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.BaseLoadBalancer;
import com.netflix.loadbalancer.Server;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.CollectionUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;

/**
 * 扩展Ribbon-同一集群优先调用
 */
@Slf4j
public class NacosSameClusterWeightedRule extends AbstractLoadBalancerRule {

    @Autowired
    private NacosDiscoveryProperties nacosDiscoveryProperties;

    @Override
    public void initWithNiwsConfig(IClientConfig iClientConfig) {

    }

    @Override
    public Server choose(Object o) {
        try {
            // 拿到配置文件中的集群名称
            String clusterName = nacosDiscoveryProperties.getClusterName();

            BaseLoadBalancer loadBalancer = (BaseLoadBalancer) this.getLoadBalancer();
            //想要请求的微服务的名称
            String name = loadBalancer.getName();

            // 拿到服务发现相关的API
            NamingService namingService = nacosDiscoveryProperties.namingServiceInstance();

            // 1，找到指定服务的所有实例A
            List<Instance> instances = namingService.selectInstances(name, true);
            // 扩展Ribbon-基于元数据的版本控制 http://www.imooc.com/article/288674
            // instances.get(0).getMetadata()

            // 2.过滤出相同集群下的所有实例B
            List<Instance> sameClusterInstances = instances.stream()
//                    .filter(instance -> {
//                        return Objects.equals(instance.getClusterName(), clusterName);
//                    })
                    .filter(instance -> Objects.equals(instance.getClusterName(), clusterName))
                    .collect(Collectors.toList());

            // 3.如果B是空，就用A
            List<Instance> instancesToBeChose = new ArrayList<>();
            if (CollectionUtils.isEmpty(sameClusterInstances)) {
                instancesToBeChose = instances;
                log.warn("发生跨集群的调用, name = {}, clusterName = {}, instance = {}",
                    name,
                    clusterName,
                    instances
                );
            } else {
                instancesToBeChose = sameClusterInstances;
            }
            //4.基于权重的负载均衡算法，返回1个实例
            Instance instance = ExtendBalancer.getHostByRandomWeight2(instancesToBeChose);
            log.info("选择的实例是 port = {}, instance = {}", instance.getPort(), instance);

            return new NacosServer(instance);
        } catch (NacosException e) {
            e.printStackTrace();
            log.error("发生异常了", e);
            return null;
        }
    }
}

// 别人类是 protected 可以实现它进行包装
class ExtendBalancer extends Balancer {
    public static Instance getHostByRandomWeight2(List<Instance> hosts) {
        return getHostByRandomWeight(hosts);
    }
}
